英文:
Java PriorityQueue<Integer> does not sorted by expected
问题
public static void main(String[] args) {
sortByBits(new int[]{0, 1, 2, 3, 4, 5, 6, 7, 8});
System.out.println(1);
}
public static int[] sortByBits(int[] arr) {
Map<Integer, Integer> m = new HashMap<>();
PriorityQueue<Integer> p = new PriorityQueue<>((a, b) -> {
if (m.get(a) == m.get(b)) {
return a - b;
} else {
return m.get(a) - m.get(b);
}
});
for (int i = 0; i < arr.length; i++) {
m.put(arr[i], Integer.bitCount(arr[i]));
p.offer(arr[i]);
}
int[] result = new int[p.size()];
int size = p.size();
for (int i = 0; i < size; i++) {
result[i] = p.poll();
}
return result;
}
Map m is:
0 -> 0,
1 -> 1,
2 -> 1,
3 -> 2,
4 -> 1,
5 -> 2,
6 -> 2,
7 -> 3,
8 -> 1,
I wanna sort by the values of the map in a PriorityQueue. The expected result is 0-1-2-4-8-3-5-6-7 or similar, right? However, the current result is 0-1-2-8-4-5-6-7-3. It's obvious that key 7's value is 3, the largest, so it should be at the end. But currently, it appears before 3. I don't understand why this is happening. Thank you.
英文:
I have a problem about PriorityQueue.
public static void main(String[] args) {
sortByBits(new int[]{0, 1, 2, 3, 4, 5, 6, 7, 8});
System.out.println(1);
}
public static int[] sortByBits(int[] arr) {
Map<Integer, Integer> m = new HashMap<>();
PriorityQueue<Integer> p = new PriorityQueue<>((a, b) -> {
if (m.get(a) == m.get(b)) {
return a - b;
} else {
return m.get(a) - m.get(b);
}
});
for (int i = 0; i < arr.length; i++) {
m.put(arr[i], Integer.bitCount(arr[i]));
p.offer(arr[i]);
}
int[] result = new int[p.size()];
int size = p.size();
for (int i = 0; i < size; i++) {
result[i] = p.poll();
}
return result;
}
Map m is <br />
0 -> 0,<br />
1 -> 1,<br />
2 -> 1,<br />
3 -> 2,<br />
4 -> 1,<br />
5 -> 2,<br />
6 -> 2,<br />
7 -> 3,<br />
8 -> 1,<br />
I wanna sorted by map's value in PriorityQueue, expected result is 0-1-2-4-8-3-5-6-7 or others right ,
but now is 0-1-2-8-4-5-6-7-3, it's obvious that key 7's value is 3,the biggest, should at the end...but now the end is 3, I don't know why.<br/>
Thanks you.
答案1
得分: 0
PriorityQueue将按自然顺序对项目进行排序。由于它们是整数，它们将按升序排序。
有关如何按所需方式排序的信息，请参阅此处链接。
英文:
PriorityQueue will sort items by the natural order. Since they are integers they will be sorted by ascending order.
See here for how to sort the way you need.
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